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Version 4.2 rev 06 Oct 2020
8.2 x 8.2 mm / 512 x 512 sensor
Lowest Noise Imaging EMCCD
Mechelle
4.6 c
Ross
t
alk
Cross talk is the unwanted contribution from one order crossing to the adjacent order (or orders) that shows as an extra
‘ghost’ line on the spectrum. Cross-talk amplitude depends on many parameters:
1. The
Distance between orders
: Larger distance results in smaller cross talk. This distance depends on the
optical design of the Mechelle and cannot be changed. The Mechelle has a large distance between orders
because of the patented dual prism design.
2.
Channel height
: This is software controlled and cross talk is proportional to the channel height, note that when
channel height is reduced, the amplitude of the signal will also be reduced.
3.
Slit height of fibre diameter
: Cross-talk also increases with slit height (or fibre diameter).
There is no standard definition of cross talk and all Echelle-based spectrograph manufactures (except Andor) do not
specify the cross talk.
To set up the number of orders for which crosstalk correction should be applied, open the
Mechelle Setup
screen then
select the required number from the
Crosstalk Removal Order
drop-down menu:
Figure 20: Selecting the Crosstalk Removal Options
To remove cross-talk lines, click the
button.
NOTES:
1. This function removes up to three orders. For example, if large (> 50μm) fibre is used, more than one cross
talk will be seen. Also if the sensor over-saturates and smears then more than three orders may be seen.
Please ensure that no saturation is present of the sensor during acquisition to ensure recording of the best
qualitative data.
2. When cross talk is removed, the software will show a zero value to indicate that cross talk lines have been
removed.
